U.S. patent number 6,096,480 [Application Number 08/985,872] was granted by the patent office on 2000-08-01 for photosensitive polyimidosiloxane compositions and insulating films made thereof.
This patent grant is currently assigned to Ube Industries, Ltd.. Invention is credited to Seiji Ishikawa, Hiroyuki Sakurai, Hiroshi Yasuno.
United States Patent |
6,096,480 |
Ishikawa , et al. |
August 1, 2000 |
Photosensitive polyimidosiloxane compositions and insulating films
made thereof
Abstract
A photosensitive polyimidosiloxane composition comprising a
polyimidosiloxane comprising 15-80 mole percent of the units,
##STR1## wherein X represents CO, O or a direct bond and R.sub.3
represents an aromatic residue containing a photosensitive group
with an unsaturated hydrocarbon group, and 85-20 mole percent of
the units, ##STR2## wherein X is as defined above, each R.sub.4
independently represents a divalent hydrocarbon residue, each
R.sub.5 independently represents an alkyl group of 1-3 carbon atoms
and 1 represents an integer of 3-30, a finely divided inorganic
filler, and an organic solvent. The composition provides films
having excellent light transmittance.
Inventors: |
Ishikawa; Seiji (Ichihara,
JP), Yasuno; Hiroshi (Ichihara, JP),
Sakurai; Hiroyuki (Ichihara, JP) |
Assignee: |
Ube Industries, Ltd. (Ube,
JP)
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Family
ID: |
27319674 |
Appl.
No.: |
08/985,872 |
Filed: |
December 5, 1997 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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687035 |
Jul 25, 1996 |
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Foreign Application Priority Data
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Jul 28, 1995 [JP] |
|
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7-192794 |
Jun 11, 1996 [JP] |
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8-149050 |
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Current U.S.
Class: |
430/283.1;
522/99; 525/421; 528/26 |
Current CPC
Class: |
C08G
73/1042 (20130101); C08G 73/106 (20130101); C08G
77/455 (20130101); C09D 183/10 (20130101); G03F
7/0387 (20130101); C09D 183/10 (20130101); C08L
2666/54 (20130101) |
Current International
Class: |
C08G
73/00 (20060101); C08G 73/10 (20060101); C08G
77/00 (20060101); C08G 77/455 (20060101); C09D
183/10 (20060101); G03F 7/038 (20060101); G03F
007/038 () |
Field of
Search: |
;430/283.1 ;522/99
;525/421 ;528/26 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
English Transaction of Japanese Kokai Patent Application 3-71633,
by United States Patent and Trademark Office, Jul. 1997
(PT097-4442), Mar. 27, 1991. .
European Patent Application No. 0,459,809 to Nakajima et al. dated
Dec. 4, 1991. .
Japanese Laid Open Patent Publication No. 8-76376 to Shinetsu
Kagaku Kogyo K.K. dated Mar. 22, 1996 (including an English
language description). .
Japanese Laid Open Patent Publication No. 57-131227 to Sugihara
dated Aug. 14, 1982 (including an English language abstract). .
Japanese Laid Open Patent Publication No. 2-50161 to Nobuyuki et
al. dated Feb. 20, 1990 (including an English language abstract).
.
Japanese Laid Open Patent Publication No. 4-252227 to Eguchi dated
Sep. 8, 1992 (including an English language abstract). .
Patent Abstracts of Japan, vol. 14, No. 219, p. 1045, Sumitomo
Bakelite Co., Ltd., "Photosensitive Resin Composition," Publication
No. 2-50161, Feb. 20, 1990. .
Japanese Laid Open Patent Publication No. 3-71633 to Takeuchi et
al., dated Mar. 27, 1991. .
Japanese Laid Open Patent Publication No. 6-11832 to Okunoyama
dated Jan. 21, 1994. .
Takeuchi et al. 115:172528, Chemical Abstracts, on line from
Columbis, Ohio of JP 6-11832, published Jan. 21, 1994 with Registry
No. 26374-94-4, 535-87-5, and 1823-59-2, on line, cited in
Abstract. .
Takeuchi et al., 03-71633, Patent Abstract of Japan, Abstract Group
No. E1078, vol. 15, No. 236, Abstract published Jun. 18, 1991 of JP
3-71633. .
Takeuchi et al., AN 91-135616, Derwent Information Ltd., on line
English Abstract of JP 3-761633A..
|
Primary Examiner: Hamilton; Cynthia
Attorney, Agent or Firm: Finnegan, Henderson, Farabow,
Garrett & Dunner, L.L.P.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
This is a continuation-in-part of application Ser. No. 687,035,
filed on Jul. 25, 1996, now abandoned.
Claims
What is claimed is:
1. A photosensitive polyimidosiloxane composition comprising:
a polyimidosiloxane comprising 15-80 mole percent of the units,
##STR6## wherein X represents a direct bond and R.sub.3 represents
an aromatic residue containing a photosensitive group with an
unsaturated hydrocarbon group, and 85-20 mole percent of the units,
##STR7## wherein X is as defined above, each R.sub.4 independently
represents a divalent hydrocarbon residue, each R.sub.5
independently represents an alkyl group of 1-3 carbon atoms or a
phenyl group and 1 represents an integer of 3-30,
a finely divided inorganic filler, and
an organic solvent
wherein an insulating film of a thickness of 2-50 .mu.m obtained
from said photosensitive polyimidosiloxane composition has a
resolution of at least 10 .mu.m after photocuring by irradiation
with a superhigh-pressure mercury lamp (2 kW) on a dried film
prepared from said photosensitive polyimidosiloxane composition,
immersing the photocured film in a triglyme solvent and washing off
the uncured portions, and then washing the surface with methanol to
obtain a relief pattern adhering to the polyimide film which is
then heat treated at 160.degree. C. for 120 minutes.
2. A photosensitive polyimidosiloxane composition according to
claim 1, wherein the finely divided inorganic filler is selected
from the group consisting of silica, talc, Wallastonite and calcium
carbonate powders.
3. A photosensitive polyimidosiloxane composition according to
claim 1, wherein the finely divided inorganic filler is contained
in an amount of 10-100 parts by weight per 100 parts by weight of
the polyimidosiloxane.
4. A photosensitive polyimidosiloxane composition according to
claim 1, wherein the solid concentration consisting of the
polyimidosiloxane is 20 to 50 wt %.
5. A photosensitive polyimidosiloxane composition according to
claim 1, wherein at least one of a sensibilizer,
photopolymerization initiator, adhesion-improving agent and
air-shutting agent is added in a total amount of 1-50 wt % with
respect to the photosensitive polyimidosiloxane.
6. A photosensitive polyimidosiloxane composition according to
claim 1, wherein the polyimidosiloxane is prepared by
polymerization and imidation of substantially equimolar amounts
of:
an aromatic tetracarboxylic dianhydride component represented by
the following general formula (1)
wherein R.sub.1 and R.sub.2 each represent mononuclear aromatic
residues with acid anhydride groups and X represents a direct bond,
and
a diamine component consisting of 15-80 mole percent of an aromatic
diamine compound containing a photosensitive group, represented by
the following general formula (2)
wherein R.sub.3 represents an aromatic residue containing a
photosensitive group with an unsaturated hydrocarbon group, and
85-20 mole percent of a diaminopolysiloxane represented by the
following general formula (3) ##STR8## wherein each R.sub.4
independently represents a divalent hydrocarbon residue, each
R.sub.5 independently represents an alkyl group of 1-3 carbon atoms
or a phenyl group and l represents an integer of 3-30.
7. A photosensitive polyimidosiloxane composition according to
claim 6, wherein the aromatic tetracarboxylic dianhydride component
is 2,3,3',4'-biphenyltetracarboxylic dianhydride.
8. A photosensitive polyimidosiloxane composition according to
claim 1, wherein the polyimidosiloxane is prepared by
polymerization and imidation of an aromatic tetracarboxylic
dianhydride component represented by the general formula (1)
wherein R.sub.1 and R.sub.2 each represent mononuclear aromatic
residues with acid anhydride groups an X represents a direct bond,
an aromatic diamine component having a --OH or --COOH group and
diaminopolysiloxane represented by the general formula (3) ##STR9##
wherein each R.sub.4 independently represents a divalent
hydrocarbon residue, each R.sub.5 independently represents an alkyl
group of 1-3 carbon atoms or a phenyl group and l represents an
integer of 3 -30 to form a polyimidosiloxane having a --OH or
--COOH group, and reaction of the resulting polyimidosiloxane with
a (meth)acryloyl compound.
9. A photosensitive polyimidosiloxane composition according to
claim 8, wherein the aromatic diamine component having a --OH or
--COOH group is 3,3'-dihydroxy-4,4'-diaminodiphenyl ether or
5,5'-methylene-bis[2-aminobenzoic acid].
10. A photosensitive polyimidosiloxane composition according to
claim 8, where the (meth)acryloyl compound is glycidyl
methacrylate, glycidyl acrylate or a half-epoxy (meth)acrylate.
11. A photosensitive polyimidosiloxane composition according to
claim 1, wherein the insulating film is formed on a circuit
board.
12. A photosensitive polyimidosiloxane composition according to
claim 1, wherein the insulating film has a soldering heat
resistance of 250-300.degree. C.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to novel aromatic polyimidosiloxanes
with excellent solubility in organic solvents and containing
photosensitive groups in their main polymer chains. More
specifically, the present invention relates to organic
solvent-soluble photosensitive polyimidosiloxanes providing
photocured products with excellent heat resistance, electrical
properties and mechanical properties including flexibility, which
are suitable as overcoat materials for flexible wiring boards,
interlayer insulating materials, or materials for forming
insulating films on solid elements and passivation films for
industrial semiconductors.
2. Description of the Related Art
Overcoat materials for flexible wiring boards, interlayer
insulating films for multilayer boards, materials for forming
insulating films on solid elements and passivation films for
industrial semiconductors, as well as interlayer insulating
materials for semiconductor integrated circuits and multilayer
printed wiring boards, require excellent heat resistance and
insulating properties, and photosensitive heat resistant materials
are being sought to meet the demand for high density and high
integration.
A number of ideas have been devised for forming such insulating
films of polyimides, due to their high heat resistance and
insulating properties.
However, commonly used polyimides are either insoluble in solvents
and have no photosensitive groups, or the polymers containing
photosensitive groups are all in the form of polyimide precursors,
i.e. polyamic acids, modified by amidation or esterification of the
carboxylic acid, and must have the polyamic acids converted into
polyimides during photocuring, or be post-baked into polyimides
after photocuring.
There also exist heat-resistant photoresist compositions prepared
by mixing organic solvent-soluble polyimides (without
photosensitive groups) with monomers which contain a photocurable
group and subjecting the mixture to photocuring (see, for example,
Japanese Unexamined Patent Publication No. 54-109828), but such
compositions have inferior photocuring properties, while the heat
resistance of the polyimides after photocuring is insufficient. In
addition, since aromatic polyimides with superior heat resistance
generally have inferior solubility in solvents, they are not
suitable for the formation of relief patterns which involves a step
of dissolving the unexposed parts after photocuring.
Ideas have also been proposed for obtaining polyimides with
excellent photosensitivity and heat resistance by reacting a
tetracarboxylic dianhyride with a diamine compound containing a
photocrosslinkable unsaturated double bond, such as diaminochalcone
(see, for example, Japanese Unexamined Patent Publication No.
57-131227).
However, although polyimides obtained in this manner have excellent
photosensitivity, their inferior solubility in organic solvents
results in longer times required for dissolution, thus constituting
a practicality problem for the formation of relief patterns.
Polyimidosiloxanes have also been proposed in order to obtain
flexible photosensitive polyimides (Japanese Unexamined Patent
Publication Nos. 2-50161, 4-252227), but since polyamic acids are
used as the polymer components, high-temperature heating is
necessary after patterning to accomplish imidation, thus
constituting a practicality problem in that thermal damage can
occur in the board.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a
photosensitive polyimidosiloxane composition having substantially
no practicality problems.
It is another object of the present invention to provide an
electrical insulating film with satisfactory resolution, which can
be formed to a large thickness and requires no high-temperature
heating (250-400.degree. C.) for imidation after patterning.
The present invention provides a photosensitive polyimidosiloxane
composition comprising:
a polyimidosiloxane comprising 15-80 mole percent of the units,
##STR3## wherein X represents CO, O or a direct bond and R.sub.3
represents an aromatic residue containing a photosensitive group
with an unsaturated hydrocarbon group, and 85-20 mole percent of
the units, ##STR4## wherein X is as defined above, each R.sub.4
independently represents a
divalent hydrocarbon residue, each R.sub.5 independently represents
an alkyl group of 1-3 carbon atoms and l represents an integer of
3-30,
a finely divided inorganic filler, and
an organic solvent,
the photocured product of said photosensitive polyimidosiloxane
composition exhibiting excellent light transmittance.
The present invention also provides an insulating film obtained
from the photosensitive polyimidosiloxane composition according to
the present invention, which has a thickness of 2-50 .mu.m and a
resolution of at least 10 .mu.m after photocuring by irradiation
with a superhigh-pressure mercury lamp (2 kW) on a dried film
prepared from the photosensitive polyimidosiloxane composition.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The polyimidosiloxane usable for the photosensitive
polyimidosiloxane composition according to the present invention
may be prepared by polymerization and imidation of substantially
equimolar amounts of:
an aromatic tetracarboxylic dianhydride component represented by
the following general formula (1)
wherein R.sub.1 and R.sub.2 each represent mononuclear aromatic
residues with acid anhydride groups and X is as defined above,
and a diamine component consisting of 15-80 mole percent of an
aromatic diamine compound containing a photosensitive group,
represented by the following general formula (2)
wherein R.sub.3 is as defined above, and 85-20 mole percent of a
diaminopolysiloxane represented by the following general formula
(3) ##STR5## wherein R.sub.4, R.sub.5 and l are as defined
above.
The polyimidosiloxanes may be produced by random or block
polymerization of substantially equimolar amounts of an aromatic
tetracarboxylic dianhydride and two types of diamine components,
represented by the general formulas given above, in an organic
solvent, followed by chemical imidation of the resulting polyamic
acid.
The aromatic tetracarboxylic dianhydride represented by general
formula (1) above may be a biphenyltetracarboxylic dianhydride,
benzophenonetetracarboxylic dianhydride or oxydiphthalic anhydride,
preferred among which are 3,3',4,4'-benzophenonetetracarboxylic
dianhydride and 2,3,3',4'-biphenyltetracarboxylic dianhydride
(a-BPDA).
The photosensitive group-containing aromatic diamine represented by
general formula (2) above may be any aromatic diamine with a
photosensitive unsaturated hydrocarbon group, examples of which
include unsaturated benzoic acid esters such as 3,5-diaminobenzoic
ethylacrylic acid ester, 2,4-diaminobenzoic ethylacrylic acid
ester, 3,5-diaminobenzoic ethylmethacrylic acid ester,
2,4-diaminobenzoic ethylmethacrylic acid ester, 3,5-diaminobenzoic
glycidylacrylate ester, 2,4-diaminobenzoic glycidylacrylate ester,
3,5-diaminobenzoic glycidylmethacrylate ester, 2,4-diaminobenzoic
glycidylmethacrylate ester, 3,5-diaminobenzoic cinnamyl ester and
2,4-diaminobenzoic cinnamyl ester; benzyl (meth)acrylates such as
3,5-diaminobenzyl acrylate and 3,5-diaminobenzyl methacrylate;
unsaturated diphenylether esters such as
4-acrylamido-3,4'-diaminodiphenyl ether,
2-acrylamido-3,4'-diaminodiphenyl ether,
2-acrylamido-3,4'-diaminodiphenyl ether,
4-cinnamamido-3,4'-diaminodiphenyl ether,
3,4'-diacrylamido-3',4-diaminodiphenyl ether,
3,4'-dicinnamamido-3',4-diaminodiphenyl ether,
4-methyl-2'-carboxyethylmethacrylic acid ester-3,4'-diaminodiphenyl
ether [carboxyethylmethacrylic acid ester: CH.sub.2
.dbd.C(CH.sub.3)COOCH.sub.2 CH.sub.2 OOC--], and
4-methyl-2'-carboxyethylacrylic acid ester-3,4'-diaminodiphenyl
ether [carboxyethylacrylic acid ester: CH.sub.2 .dbd.CHCOOCH.sub.2
CH.sub.2 OOC--]; and substituted or unsubstituted diaminochalcones
such as 4,4'-diaminochalcone, 3,3'-diaminochalcone,
3,4'-diaminochalcone, 3',4-diaminochalcone,
4'-methyl-3',4-diaminochalcone, 4'-methoxy-3',4-diaminochalcone and
3'-methyl-3,5-diaminochalcone.
A single photosensitive group-containing aromatic diamine
represented by general formula (2) above may be used, or 2 or more
thereof may be used in combination.
The diaminopolysiloxane represented by general formula (3) above
preferably is one wherein R.sub.4 in general formula (3) is a
divalent hydrocarbon residue, preferably a "polymethylene" group of
2-6 carbon atoms, particularly 3-5 carbon atoms, or a phenylene
group, R.sub.5 is independently an alkyl group of 1-3 carbon atoms
such as a methyl, ethyl, propyl or a phenyl group, and l is 3-30,
especially 5-20. So long as l is in the aforementioned range
(3-30), the diaminopolysiloxane represented by general formula (3)
may be a homogeneous compound, or it may be a mixture of compounds
with different values for l. In the case of a mixture, the average
value for l is preferably in the range of 5-20, as calculated based
on amino equivalents.
According to the present invention, the diamine components may be a
photosensitive group-containing aromatic diamine represented by
general formula (2) above and a diaminopolysiloxane represented by
general formula (3) above, and the aromatic diamine represented by
general formula (2) may be used in a proportion of 15-80 mole
percent, preferably 20-70 mole percent, and the diaminopolysiloxane
represented by general formula (3) in a proportion of 85-20 mole
percent, preferably 80-30 mole percent.
If the proportion of the photosensitive group-containing aromatic
diamine represented by general formula (2) is less than the minimum
given above, then the photosensitivity of the resulting
photosensitive polyimidosiloxane may be reduced, a high resolution
electrical insulating film may not be obtained after photocuring,
and the thermal decomposition temperature of the photosensitive
polyimidosiloxane may be lowered. If the proportion of the
photosensitive group-containing aromatic diamine represented by
general formula (2) is greater than the maximum given above, then
the organic solubility of the resulting photosensitive
polyimidosiloxane may be reduced.
Other aromatic diamines may also be used in addition to the
diamines represented by general formulas (2) and (3). These are
preferably used at not more than 65 mole percent, more preferably
not more than 30 mole percent of the diamine component. Other
suitable aromatic diamines include, for example, aromatic diamines
with two benzene rings such as 4,4'-diaminodiphenyl ether,
4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone and
o-tolidine; aromatic diamines with 3 benzene rings such as
1,4-bis(4-aminophenoxy)benzene and 1,4-bis(4-aminophenyl)benzene;
and aromatic diamines with 4 benzene rings such as
bis[4-(4-aminophenoxy)phenyl]sulfone and
2,2-bis[4-(4-aminophenoxy)phenyl]propane.
The photosensitive polyimidosiloxane may preferably be obtained by
first subjecting an aromatic tetracarboxylic dianhyride component
and a substantially equimolar amount of a diamine component to a
random or block polymerization reaction, preferably a random
polymerization reaction, for about 1-48 hours in an organic solvent
at a reaction temperature of 100.degree. C. or lower, preferably at
a reaction temperature of 10-80.degree. C., and then diluting the
polyamic acid solution resulting from the polymerization reaction
with an organic solvent, and adding a chemical imidating agent, for
example a carboxylic anhydride such as acetic anhydride or a
tertiary amine such as pyridine, at a temperature of 100.degree. C.
or lower, preferably at a reaction temperature of 10-50.degree. C.,
for imidation reaction for about 0.1 to 5 hours.
The organic solvent used for the above-mentioned polymerization
reaction and imidation reaction may be, for example,
N,N-dimethylsulfoxide, N,N-dimethylformamide, N,N-diethylformamide,
N,N-dimethylacetoamide, N,N-diethylacetoamide,
N-methyl-2-pyrrolidone (NMP) or hexamethylenephosphoamide.
Alternatively, the photosensitive polyimidosiloxane may be prepared
by polymerization and imidation of an aromatic tetracarboxylic
dianhydride component represented by the above-mentioned general
formula (1), an aromatic diamine component having a --OH or --COOH
group such as 3,3'-dihydroxy-4,4'-diaminodiphenyl ether or
5,5'-methylene-bis[2-aminobenzoic acid] and a diaminopolysiloxane
represented by the above-mentioned general formula (3) to form a
polyimide, and reaction of the resulting polyimide with a
(meth)acryloyl compound such as glycidyl methacrylate, glycidyl
acrylate or, preferably, a half-epoxy (meth)acrylate (the half
number of epoxy groups of an epoxy compound having about 10 epoxy
groups are replaced by (meth)acrylate groups) under an inert gas
atmosphere such as N.sub.2 at a low temperature.
The photosensitive polyimidosiloxane may be used without
modification, or depending on the use, for example when used as a
pattern-forming material, it is preferably used as a solution in an
organic solvent.
The aforementioned organic solvent used for the photosensitive
polyimidosiloxane composition according to the present invention
may be a sulfoxide-based solvent such as dimethylsulfoxide or
diethylsulfoxide, a formamide-based solvent such as
N,N-dimethylformamide or N,N-diethylformamide, an acetoamide-based
solvent such as N,N-dimethylacetoamide or N,N-diethylacetoamide, a
pyrrolidone-based solvent such as N-methyl-2-pyrrolidone,
N-ethyl-2-pyrrolidone or N-vinyl-2-pyrrolidone, a glyme-based
solvent such as methyldiglyme or methyltriglyme, or
hexamethylphosphoric triamide, .gamma.-butyllactone or
cyclohexanone.
The polymer solid concentration in the photosensitive
polyimidosiloxane composition of the invention is preferably 20-50
wt %.
A sensitizer and photopolymerization initiator as well as an
adhesion-improving agent such as a thermosetting resin or melamine
resin and an air-shutting agent such as vaseline or paraffin wax
are preferably also added to the photosensitive polyimidosiloxane
composition.
A photopolymerizable compound with an ethylenic unsaturated group
may also be added within a range which does not impair the
properties of the insulating film after photocuring.
The aforementioned sensibilizer or photopolymerization initiator
may be Michler's ketone, benzoin, benzoin methyl ether, benzoin
ethyl ether, benzoin isopropyl ether, 2-t-butylanthraquinone,
1,2-benzo-9,10-anthraquinone, 4,4'-bis(diethylamino)benzophenone,
acetophenone, benzophenone, thioxanthone, 1,5-acenaphthene,
1-hydroxy-cyclohexylphenyl ketone,
2-benzyl-1,2-dimethylamino-1-(4-morpholinophenyl)butane-1,1-hydroxy-cycloh
exylphenyl ketone, etc., and these are preferably added in a total
of 1-50 parts by weight, and especially 10-50 parts by weight, with
respect to 100 parts by weight of the polyimidosiloxane.
The above-mentioned photopolymerizable compound having an ethylenic
unsaturated group may be ethyleneglycol di(meth)acrylate,
propyleneglycol di(meth)acrylate, trimethylolpropane
tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate,
N,N'-methylene bis(meth)acrylate, diethylaminoethyl (meth)acrylate,
1,3,5-triacryloylhexahydro-s-triazine, tris(hydroxyethylacryloyl)
isocyanate, (meth)acryloxyethyl phosphate or
bis[(meth)acryloxyethyl]phosphate.
The photosensitive polyimidosiloxane composition of the invention
contains a finely divided inorganic filler such as Wallastonite,
silica, talc or calcium carbonate powder preferably in an amount of
10-100 parts by weight per 100 parts by weight of the
photosensitive polyimidosiloxane.
A pattern may be formed by using the photosensitive
polyimidosiloxane composition as mentioned above.
For example, the above-mentioned photosensitive polyimidosiloxane
composition may be first applied onto a board and then dried to
remove the organic solvent. The application onto the board may be
accomplished by screen printing, a curtain roll, a reverse roll, or
the like. The applied film (preferably with a thickness of 5-100
.mu.m, and especially 10-100 .mu.m) is dried at 90.degree. C. or
lower, and preferably 40-80.degree. C. After drying, a negative
photomask is placed on the dried applied film which is then
irradiated with activating light rays such as ultraviolet rays,
visible light rays or electron rays. A polyimidosiloxane pattern
may then be obtained by washing the unexposed portions with a
developing agent using a shower or ultrasonic waves. The thickness
of the cured film is preferably about 2-50 .mu.m.
The developing agent may be an organic solvent such as
N,N-dimethylformamide, N,N-dimethylacetoamide, dimethylsulfoxide,
N-methyl-2-pyrrolidone, hexamethylenephosphoamide, diglyme,
triglyme, or a mixture thereof with methanol, ethanol or the
like.
The photosensitive polyimidosiloxane as mentioned above is very
readily soluble, and thus the polyimidosiloxane in the unexposed
portions is easily removed to allow ready formation of a
pattern.
Many other excellent effects are provided, in that since the
photosensitive polyimidosiloxane composition of the invention have
high photosensitivity and excellent light transmittance and
photocrosslinkability, there is no need for a separate resist for
image formation as with non-photosensitive polyimides of the prior
art, and since there is no need for high-temperature heating
(250-400.degree. C.) for imidation after image formation as with
photosensitive polyamic acids, an after-heating step at
150-200.degree. C. being sufficient, not only are high reliability
and lower cost afforded, but thermal damage to the boards is also
avoided. The photosensitive polyimidosiloxane composition of the
invention may therefore be suitably used for the formation of both
negative patterns and positive patterns.
Furthermore, patterns made with cured films formed from
photosensitive polyimidosiloxane compositions of the invention have
excellent heat resistance and electrical and mechanical properties,
and especially excellent flexibility. For example, an insulating
film according to the invention, suitably with a thickness of about
2-50 .mu.m, has a post-photocuring resolving power of at least 10
.mu.m, and usually about 10-1000 .mu.m. Thus, the insulating film
according to the invention is particularly suited as an insulating
material for high-density flexible boards.
Examples of the present invention will now be provided.
Evaluation of the following examples was conducted in the following
manner.
(Property tests)
1. Inherent viscosity
The inherent viscosity (In .eta./c) was measured at 30.degree. C.
in a solution containing 0.5 g of a polymer in 100 ml of
N-methyl-2-pyrrolidone.
2. Polyimidosiloxane film formability
A solution of 20 g polyimidosiloxane dissolved in 100 ml
N-methyl-2-pyrrolidone was applied onto a Teflon plate (1.0 mm) to
a polyimidosiloxane film thickness of approximately 20 .mu.m and
dried at 70.degree. C. for 30 minutes, and the occurrence of cracks
upon heating at 160.degree. C. for 60 minutes and 180.degree.
bending was observed. Absence of cracking was indicated by
".largecircle.", and cracking was indicated by ".times.".
3. Solubility of polyimidosiloxane in NMP
A 0.2 g portion of polyimidosiloxane was added to 0.8 g of
N-methyl-2-pyrrolidone, and the state of dissolution of the
polyimidosiloxane was observed, indicating dissolution for up to 1
hour by "*", dissolution for up to one day by ".largecircle.",
swelling alone by ".DELTA.", and no dissolution by ".times.".
4. Thermal decomposition temperature
This was measured using a thermogravimetric analyzer.
5. Evaluation of photocuring property
A dam was constructed using a polyimide film as the spacer, a bar
coater was used for uniform casting of ink on copper foil (35
.mu.m), and the dried film obtained from drying at 70.degree. C.
for 30 minutes was subjected to the photosensitivity and resolving
power tests described
below.
Photosensitivity
The dried film was irradiated using a superhigh-pressure mercury
lamp (2 kW) at an illuminance of 7 mW/cm.sup.2, and the amount of
light irradiation required for photocuring was recorded.
Resolution
A negative film (a test pattern containing an equally-spaced figure
pattern having a line width and spacing of 0.075-2.0 mm) was placed
on the dried film, and a superhigh-pressure mercury lamp (2 kW) was
used to produce a prescribed degree of irradiation for photocuring,
after which it was immersed in a triglyme solvent and the uncured
portions were washed off, the surface was washed with methanol to
obtain a relief pattern adhering to the polyimide film which was
then heat treated at 160.degree. C. for 120 minutes, and the
resolution of the pattern was measured.
6. Measurement of mechanical properties
The photosensitive polyimidosiloxane composition was coated onto a
polytetrafluoroethylene film and dried at 70.degree. C. for 30
minutes, and after subsequent 1 J/cm.sup.2 ultraviolet light
exposure and heating at 200.degree. C. for one hour, the film was
peeled off, a dumbbell-shaped test piece was cut out, and a tension
tester was used for measurement according to ASTM D882 to determine
the tensile strength, elongation rate and initial elastic
modulus.
7. Electrical properties
The photosensitive polyimidosiloxane composition was applied onto a
0.3 mm-thick copper plate and dried at 70.degree. C. for 30
minutes, and the sample obtained by subsequent 1 J/cm.sup.2
ultraviolet light exposure and heating at 200.degree. C. for one
hour was subjected to testing based on JIS C 2103 (electrical
insulation varnish test method).
EXAMPLE 1
(Amic acid synthesis step)
After addition of 25.06 g (0.085 mol) of
2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA) and 108 g
NMP to a 1 liter-volume reactor equipped with a dropping funnel and
a nitrogen admission tube, and thorough dissolution, 1.2 g of
hydroquinone and 1.2 g of 4-methoxyhydroquinone were added as
anti-gelating agents. The solution was cooled with dry ice/methanol
(-30.degree. C.) while circulating drying air, after which 6.0 g
(0.023 mol) of 3,5-diaminobenzoic ethylmethacrylic acid ester
[melting point: 88-89.degree. C., elemental analysis (found, %): C:
59.36, H: 6.08, N: 10.49] and 54.0 g (0.062 mol)
diaminopolysiloxane [R.sub.4 being propyl, R.sub.5 being methyl and
l being 10 in general formula (3); amino equivalents: 435] were
added over 3 to 5 minutes. The equipment was washed in the
apparatus with 40 g NMP. External cooling was followed by stirring
at 25-28.degree. C. for 20-30 minutes to obtain a polyamic acid
solution.
(Chemical imidation step)
A 472 g portion of NMP was then added to the same reactor to dilute
the reaction solution. Next, 145.2 g acetic anhydride and 62.2 g
pyridine were added with the dropping funnel over 10 minutes at
25-28.degree. C. while externally cooling, and the mixture was
stirred overnight at 18-22.degree. C. to obtain the imidated
solution.
(Precipitation/filtration/washing/drying step)
The above-mentioned imidated solution was precipitated using a
disperser for 2 minutes in a 3-liter container containing 1.5
liters of methanol.
The precipitate was filtered out using filter paper (No.3, product
of Advantech) and washed with a small amount of methanol. This
procedure was repeated 3 times, after which the filtrated solid was
vacuum-dried (25.degree. C., 15 minutes) to obtain 85.5 g of a
photosensitive polyimidosiloxane.
(Inking step)
After dissolving 30 g of the above-mentioned photosensitive
group-containing polyimidosiloxane in 45 g NMP, 5.25 g of Aerosil
(average particle size: approx. 0.02 .mu.m), 12 g of talc (average
particle size: 1.5 .mu.m), 6.92 g of 1-hydroxy-cyclohexylphenyl
ketone and 6.92 g of
2-benzyl-1,2-dimethylamino-1-(4-morpholinophenyl)butane-1 were
added thereto and mixed. The mixture was kneaded with a triple
roller to obtain an ink/photosensitive polyimidosiloxane solution
composition.
The results from evaluation of the photosensitive polyimidosiloxane
solution composition are summarized in Table 2.
Measurement of the mechanical properties of the exposed and
heat-treated film revealed a tensile strength of 0.93 kg/mm.sup.2,
an elongation of 9% and an initial elastic modulus of 33
kg/mm.sup.2.
Measurement of the electrical properties of the exposed and
heat-treated film revealed a volume resistance value of
9.2.times.10.sup.14 .OMEGA..multidot.cm.
When the soldering heat resistance of the insulating film was
evaluated by conventional methods, no problems were found up to
300.degree. C.
EXAMPLE 2
A photosensitive polyimidosiloxane was obtained in the same manner
as Example 1, except that benzophenonetetracarboxylic dianhydride
(BTDA) was used instead of 2,3,3',4'-biphenyltetracarboxylic
dianhydride.
A photosensitive polyimidosiloxane solution composition (ink) was
then obtained in the same manner as described in Example 1.
When the soldering heat resistance of the photocured photosensitive
polyimidosiloxane (insulating film) was evaluated by conventional
methods, no problems were found up to 300.degree. C.
The results of evaluation of the other properties are summarized in
Tables 1 and 2.
EXAMPLES 3-5
Photosensitive polyimidosiloxanes were obtained in the same manner
as Example 1, except that the photosensitive group-containing
aromatic diamines listed in Table 1 were used instead of the
3,5-diaminobenzoic ethylmethacrylic acid ester of Example 1.
Photosensitive polyimidosiloxane solution compositions (inks) were
then obtained in the same manner as described in Example 1.
The soldering heat resistance of the insulating films obtained from
the photosensitive polyimidosiloxane solutions were evaluated by
conventional methods. No problems were found in any of these up to
300.degree. C.
The results of evaluation of the other properties are summarized in
Tables 1 and 2.
COMPARATIVE EXAMPLE 1
A photosensitive polyimidosiloxane was obtained in the same manner
as Example 1, except that no diaminosiloxane was used. The
resulting photosensitive polyimidosiloxane was insoluble in
N-methylpyrrolidone, and thus measurement of the photocuring
properties could not be made.
COMPARATIVE EXAMPLE 2
A photosensitive polyimidosiloxane was obtained in the same manner
as Example 1, except that pyromellitic dianhydride was used instead
of 2,3,3',4'-biphenyltetracarboxylic dianhydride (PMDA).
The resulting photosensitive polyimidosiloxane merely swelled in
N-methylpyrrolidone, making it impossible to obtain an ink solution
and measure the photocuring properties.
COMPARATIVE EXAMPLE 3
Production of base polymer
A polyimidosiloxane solution was obtained by reacting 17.140 g
(0.0582 mol) a-BPDA, 26.16 g (0.0291 mol) diaminopolysiloxane (450
amino equivalents) and 4.424 g (0.0291 mol) diaminobenzoic acid in
54 g NMP at 170.degree. C. for 3 hours.
Epoxy reaction
A 17 g portion of the above-mentioned polyimidosiloxane solution
was taken (0.011 mol of diaminobenzoic acid), 4.51 g (0.032 mol) of
glycidyl methacrylate in a 3-fold amount with respect to carboxyls
was added, and the reaction was conducted at 90.degree. C. for 3
hours while circulating dry air. The resulting epoxy-modified
solution was blackish brown.
Mixing
With 25.0 g of the epoxy modified solution (12.7 g solid portion)
there were mixed 3.8 g of talc, 2.5 g of Aerosil 200, 0.38 g of
DB-100, 0.97 g of Irgacure 369 and 1.95 g of Irgacure 184, to
obtain a photosensitive polyimidosiloxane solution composition
(ink) of a color shade of blackish brown.
Evaluation of photocuring properties
After forming a film from the photosensitive polyimidosiloxane
solution in the same manner as Example 1, it was photocured by
irradiation with 1.0 J/cm.sup.2 ultraviolet light and then immersed
in a triglyme solvent, and upon exposure of the uncured portions to
ultrasonic waves and washing off of the unexposed portions,
floating of the film and surface roughness were observed.
EXAMPLE 6
The photosensitive polyimidosiloxane solution (ink) of Example 1
was used for a separate resolving power evaluation according to the
following method.
Test pattern
A glass mask test pattern (positive pattern) was used for the
resolving power test. The pattern had sizes of 4 .mu.m.phi., 6
.mu.m.phi., 8 .mu.m.phi., 10 .mu.m.phi. and 15 .mu.m.phi..
Film formation
Spin coating was used for the application, with drying at
60.degree. C..times.30 minutes, light exposure at 0.21 J/cm.sup.2
and development in an ultrasonic wave bath (triglyme solvent).
Evaluation results
A 10 .mu.m.phi. hole was formed with a 3 .mu.m film thickness, and
no crumbling of the hole was observed.
TABLE 1
__________________________________________________________________________
Type of diamine component and proportion (mole %) Type of acid in
diamine component dianhydride Diamine of formula (3) Diamine of
formula (2) Diamine of formula (2)
__________________________________________________________________________
Ex. 1 a-BPDA Diaminopoly-siloxane 73 3,5-diaminobenzoic 27 --
ethylmethacrylic acid ester Ex. 2 BTDA Diaminopoly-siloxane 73
3,5-diaminobenzoic 27 -- ethylmethacrylic acid ester Ex. 3 a-BPDA
Diaminopoly-siloxane 73 3,5-diaminobenzyl 27 -- acrylate Ex. 4
a-BPDA Diaminopoly-siloxane 73 4-acrylamido-3,4'- 27 --
diaminodiphenyl ether Ex. 5 a-BPDA Diaminopoly-siloxane 73
3,5-diaminobenzoic 14 4-acrylamido- 3,4'- 13 ethylmethacrylic acid
diaminodiphenyl ether ester Comp. Ex. 1 a-BPDA --
3,5-diaminobenzoic 100 -- ethylmethacrylic acid ester Comp. Ex. 2
PMDA Diaminopoly-siloxane 73 3,5-diaminobenzoic 27 --
ethylmethacrylic acid ester
__________________________________________________________________________
TABLE 2
__________________________________________________________________________
Cured film Photocuring properties Photosensitive polyimide Thermal
Photosensitivity Inherent decomposition Film Light viscosity Film
Solubility temperature thickness irradiation Resolution (dl/g)
formability in NMP .degree. C.) (.mu.m) (J/cm.sup.2) (mm.phi.)
__________________________________________________________________________
Ex. 1 0.18 .largecircle. * 375 25 0.55 0.075 Ex. 2 0.15
.largecircle. .largecircle. 355 23 0.50 0.075 Ex. 3 0.14
.largecircle. * 380 24 0.45 0.10 Ex. 4 0.15 .largecircle. * 340 21
0.90 0.20 Ex. 5 0.14 .largecircle. * 360 25 0.85 0.15 Comp. Ex. 1
-- x 410 -- -- -- Comp. Ex. 2 -- .DELTA. 390 -- -- --
__________________________________________________________________________
EXAMPLES 7-9 AND COMPARATIVE EXAMPLE 4
The procedures as described in Example 1 were repeated to obtain
films of 25 .mu.m thick, except that no talc was added or the
amount of talc was varied. The resolution values evaluated are
shown in Table 3 below.
TABLE 3 ______________________________________ Example Amount of
talc Resolution No. (phr)* (mm.phi.)
______________________________________ Comp. 0 0.4 Ex. 4 Ex. 7 15
0.075 Ex. 8 30 0.075 Ex. 9 40 0.075
______________________________________ *phr: parts by weight per
100 parts by weight of polymer
The smaller the value (mm.phi.) for the resolution, the better the
resolution.
The photosensitive polyimidosiloxanes according to the present
invention have excellent solubility, so that the polyimidosiloxanes
in the unexposed portions can be easily removed.
Furthermore, the photosensitive polyimidosiloxanes according to the
invention have high photosensitivity, giving them excellent light
transmittance and photocrosslinkability.
Photosensitive polyimidosiloxane compositions of the invention may
also be formed to large film thicknesses, and with satisfactory
photocuring properties of resolution and photosensitivity.
Cured films formed from the photosensitive polyimidosiloxane
compositions of the invention also have excellent heat resistance
of 300.degree. C. and higher, and even 330.degree. C. and higher,
in terms of the thermal decomposition temperature, as well as
soldering heat resistance of 250-300.degree. C., film thicknesses
of 2-50 .mu.m, and post-photocuring resolution of at least 10
.mu.m, and particularly from 10 (thickness of 2 .mu.m) to 1000
.mu.m (thickness of 50 .mu.m).
Cured films formed from the photosensitive polyimidosiloxane
compositions of the invention also have excellent mechanical
properties, and electrical properties which are superior to epoxy
resins as evaluated based on volume resistance, while also having
superb flexibility with no cracks produced upon bending.
* * * * *